Compositions comprising copolymers containing polydimethylsiloxane (PDMS) moieties

Abstract

The present invention relates to a composition comprising: (1) a polymer derived from a reaction of a polydimethylsiloxane (PDMS) (1a) comprising terminal amine groups (-NH2 or -NHR), R being an alkyl group and preferably methyl or ethyl, with a compound (1b) comprising at least two isocyanate groups (-N=C=O), in order to obtain a polymer (1) comprising intrachain urea groups; (2) a polymer derived from a reaction of a polydimethylsiloxane (PDMS) (2a) comprising pendant -NH2 groups with a compound (2b) comprising a single isocyanate group (-N=C=O), in order to obtain a polymer (2) comprising pendant urea groups.

Description

Description Title of the invention: Compositions comprising copolymers containing polydimethylsiloxane (PDMS) portions Technical Field

[0001] The present invention relates to new polymer-based compositions containing polydimethylsiloxane (PDMS) parts, the use of such compositions in adhesive products intended to be applied to skin, wounds, hair and / or mucous membranes, and dressings comprising an elastomeric matrix obtained from such compositions. Previous technique

[0002] Silicone elastomers are used in numerous fields (automotive, medical devices, childcare, optics, cosmetics, etc.). In the field of adhesives, silicone elastomers are particularly valuable in a medical context, especially for application on skin, wounds, hair, nails, or mucous membranes. These are "soft" adhesives that are not aggressive to the skin, while still offering good long-term adhesion. They are also repositionable, atraumatic upon removal, and therefore well-tolerated by the skin, particularly fragile skin such as the skin around a wound. These adhesives can be applied, removed, and reapplied without leaving residue or causing redness. Silicones can be used as edges for dressings or in direct contact with the wound being treated.

[0003] However, the manufacturing processes for silicone elastomers are quite complex: whether obtained by hot or cold vulcanization, their production must adhere to very precise temperature and humidity conditions. Furthermore, due to the nature of their components and their manufacturing process, silicone elastomers are expensive.

[0004] Within the general framework of adhesive copolymers containing polydimethylsiloxane (PDMS) components, not limited to medical-type adhesive applications such as in dressings, among the previous technologies using Examples of polysiloxanes linked to other polymer segments via isocyanate or amide groups include: - US applications 2006 / 194937 and US 2006 / 036055 which describe polydimethylsiloxane (PDMS) terminated by amino groups (bisaminomethyl), reacted with diisocyanates; - US applications 2013 / 225768 and US 2007 / 148475 which describe a technology comprising the reaction of a PDMS diamine with diethyl oxalate, the product from this reaction being able to then be reacted with diamines such as ethylene diamine; - US patent 6 090902 which describes poly(ethylene-butylene) with terminal groups bearing an isocyanate residue, obtained with methacryloyl isocyanate, the resulting polymer then being reacted with a PDMS bearing a methacryl group, in the presence of 2-ethylhexyl acrylate; - US application 2021 / 0009880 which describes polyolefin-polydiorganosiloxane copolymers, the synthesis route used involving the preparation of polyethylene with -SiMe2H groups in terminal position, which can react with Si-OH groups in terminal position by PDMS; - application WO 2014 / 123775 which describes polysiloxane-polyamide copolymers whose linkage is achieved by polymerization of diacids and diamines (such as hexamethylenediamine (HDMA) and adipic acid for Nylon 6,6) with the incorporation at the end of the reaction of undecylenic acid (UDA), introducing a C=C double bond which can react with a —SiH group of a siloxane; - application CN 109384930 which describes a block copolymer of polyamide based on an aliphatic linear chain and polysiloxane; - application KR20170032726 which describes a triblock copolymer polyamideimide-polydimethylsiloxane-polyamideimide (PAI-PDMS-PAI): [Chem. 1]; - application KR20160146250) which describes polymers as follows: [Chem. 2] - the publication Song et al., Journal of Applied Polymer Science (2020), DOI: 10.1002 / APP.48753, which describes the use of quantities of approximately 5% by mass of PDMS to reduce the loss due to wear of nylon; - application FR2907676 which describes cosmetic compositions comprising organopolysiloxane-polyurea copolymers intended for makeup; - US application 2021 / 0284840 which describes compositions comprising siloxane-urethane-urea copolymers that can be used as a skin contact adhesive; - CN application 103910845 which describes a method for the synthesis of a multi-block polyamide-polysiloxane copolymer, polysiloxanes having terminal -OH groups reacting with one of the two isocyanate groups of a diisocyanate, the other isocyanate group then reacting with a terminal COOH group of a polyamide.

[0005] The present invention aims to provide physically crosslinked polydimethylsiloxane (PDMS) materials through supramolecular interactions. One objective of the present invention was to develop a material similar to, in In terms of mechanical properties (flow temperatures, storage moduli) and adhesion, chemically crosslinked PDMS currently used in dressings.

[0006] The present invention relates not only to specific copolymer compositions but also to an elastomeric matrix obtained from such compositions. Finally, the present invention relates to a dressing comprising such an elastomeric matrix, and more generally to the use of such compositions in products intended for application to the skin, wounds, hair, nails, and / or mucous membranes. Description of the invention

[0007] Thus, according to a first aspect, the present invention relates to a composition comprising: (1) a polymer formed by a reaction of a polydimethylsiloxane (PDMS) (la) comprising terminal amine groups -NH2 or -NHR, R being an alkyl group and preferably methyl or ethyl, with a compound (lb) comprising at least two isocyanate groups (-N=C=O), in order to obtain a polymer (1) comprising intrachain urea groups; (2) a polymer formed by a reaction of a polydimethylsiloxane (PDMS) (2a) having -NH2 side groups with a compound (2b) having a single isocyanate group (-N=C=O), in order to obtain a polymer (2) having urea side groups).

[0008] According to a second aspect, the present invention relates to the use of a composition according to the present invention in adhesive products intended to be applied to the skin, wounds, hair and / or mucous membranes.

[0009] According to a third aspect, the present invention relates to a dressing comprising an elastomeric matrix obtained from the composition according to the present invention. Preferably, in a dressing according to the present invention, the elastomeric matrix has through holes. In preferred dressings according to the present invention, the elastomeric matrix It further contains one or more active ingredients for wound treatment, the active ingredients being selected from the group consisting of: antibacterials, antiseptics, analgesics, anti-inflammatories, wound-healing agents, and anesthetics. In preferred dressings according to the present invention, the elastomeric matrix is ​​present in the form of an adhesive border allowing the dressing to be fixed to the skin surrounding a wound to be treated. In preferred dressings according to the present invention, the elastomeric matrix is ​​present in the form of a film having a thickness of at least 20 µm and at most 50 µm.

[0010] In the composition according to the present invention, preferably polydimethylsiloxane (PDMS) (la) comprising terminal amine groups has the following molecular formula (A): [Chem. 3] The compound (lb) comprising at least two isocyanate groups is a diisocyanate of formula (B): [Chem. 4] (B), the reaction of polydimethylsiloxane (PDMS) (la) of formula (A) with a diisocyanate (lb) of formula (B), allowing to obtain a polymer (1) comprising a chain of formula (C): [Chem. in which - x represents an integer greater than or equal to 10; - n represents an integer greater than or equal to 1; - Ri represents hydrocarbon groups which can be saturated, linear or branched and which contain between at least 1 and at most 6 carbon atoms, preferably between at least 2 and at most 4 carbon atoms, more preferably 3 carbon atoms; - R2 represents a hydrogen atom or hydrocarbon groups that may be saturated, linear or branched, and that contain between at least 1 and at most 6 carbon atoms, preferably methyl or ethyl; and - Li represents a saturated hydrocarbon group, linear or branched, cyclic or acyclic, or an unsaturated hydrocarbon group, linear or branched, comprising at least one double bond and / or at least one aromatic ring.

[0011] In the composition according to the present invention, preferably polydimethylsiloxane (PDMS) (la) comprises at least two primary amine terminal groups (-NH2), and preferably comprises terminal groups - (CH2)SNH2 and / or -(CH2)— (CH)CH3-(CH2)NH2, and / or RI can be chosen from the following groups, the symbol * indicating a branch point: (RM) [Chem. (Rl-2) [Chem. 7]

[0012] In the composition according to the present invention, preferably polydimethylsiloxane (PDMS) (la) comprises at least two secondary amine terminal groups, preferably -NH(ethyl) or -NH(methyl) groups and / or R2 can be chosen from the following groups, the symbol * indicating a branch point: (R2-1 [Chem. 8]) (R2-2) [Chem. 9] (R2-3) [Chem. 10]

[0013] In the composition according to the present invention, preferably polydimethylsiloxane (PDMS) (la), comprising at least two terminal amine groups, the starting material in the preparation of the polymer (1), has a number molecular weight (Mn) of at least 500 g.mol -1 and at most 150,000 g / mol -1 , preferably of at least 2000 g / mol -1 and at most 30,000 g / mol -1 , and / or the number of units x is at least 10 and at most 900.

[0014] In the composition according to the present invention, preferably the compound (lb) comprising at least two isocyanate groups (-N=C=O) is selected from alkyl diisocyanates, aromatic diisocyanates and / or alicyclic diisocyanates.

[0015] In the composition according to the present invention, preferably L1 is a hydrocarbon structure such that at least 4 and at most 12 carbon atoms separate the two branch points by the shortest path, and preferably L1 is chosen from the following groups, the symbol * indicating a carbon atom that is part of the structure L1 and is also a branch point: (Ll-1) [Chem. 11] (Ll-2) [Chem. 12] (Ll-3) [Chem. 13] (Ll-4) [Chem. 14] (Ll-5) [Chem. 15] among which for the (Ll-4) structure, the two isocyanate groups may be present on any of the carbon atoms in ortho, meta or para positions relative to the CH2 group located between the two aryl groups, and preferably the two isocyanate groups are in positions 4,4' or 2,4' or 2,2, and among which for the (Ll-5) structure, the two isocyanate groups may be present on any of the carbon atoms in ortho, meta or para positions relative to the CH3 group, and preferably the two isocyanate groups are in positions 2,4 or 2,6.

[0016] In the composition according to the present invention, preferably the molecule comprising at least two isocyanate groups (-N=C=O) is an aromatic diisocyanate, more preferably L1 is a hydrocarbon structure corresponding to (L1-4), and particularly preferably L1 is a hydrocarbon structure corresponding to (Ll-4) in which the two isocyanate groups are in positions 4,4'.

[0017] In the composition according to the present invention, preferably polydimethylsiloxane (PDMS) (2a) comprising amine side groups has the following molecular formula (D): [Chem. 16] It being understood that the y2 amine side groups can be found independently of each other along the chain of the PDMS polymer, the compound (2b) comprising at most one isocyanate group is a monoisocyanate of formula (E): [Chem. 17] L2— N=C=O (E), the reaction of polydimethylsiloxane (PDMS) (2a) of formula (D) with y3 molar equivalent(s) of monoisocyanate of formula (E), allowing to obtain a polymer (2) of formula (F): [Chem. 18] - yl and y 2 represent integers greater than or equal to 1; - y3 represents an integer between at least 0, preferably at least 1, and at most y2; It being understood that the amine and urea side groups can be found independently of each other along the PDMS polymer chain, - R3 represents a hydrocarbon group that can be saturated, linear or branched, and that contains between at least 1 and at most 6 carbon atoms, preferably between at least 2 and at most 4 carbon atoms, more preferably 3 carbon atoms, or R3 can be -(CH2)3-NH-(CH2)2-; and - L2 represents a saturated hydrocarbon group, linear or branched, cyclic or acyclic, or an unsaturated hydrocarbon group, linear or branched, comprising at least one double bond and / or at least one aromatic ring; a saturated hydrocarbon group, linear or branched, cyclic or acyclic, in which one or more CH2s have been replaced by O or C=O; or an unsaturated hydrocarbon group, linear or branched, comprising at least one double bond and / or at least one aromatic ring and in which one or more CH2s may have been replaced by O or C=O.

[0018] In the composition according to the present invention, preferably polydimethylsiloxane (PDMS) (2a) comprises -NH2au as side groups less primary amine pendant groups (-NH2), and preferably includes pendant groups -(CH2)3NH2 and / or -(CH2)3-(NH)-(CH2)2-NH2, and / or R3 may be chosen from the following groups, the symbol * indicating a branch point: r , (Rl-1) [Chem. (Rl-2) [Chem. 20] *-CH2-CH2-CH2-NH-CH2-CH2-*

[0019] In the composition according to the present invention, preferably the number average molecular weight Mn of polydimethylsiloxane (PDMS) (2a) comprising -NH2 side groups is at least 10 kg / mol and at most 80 kg / mol, preferably at least 20 kg / mol and at most 70 kg / mol, and more preferably at least 40 kg / mol and at most 60 kg / mol.

[0020] In the composition according to the present invention, preferably the groups -(Si(Me)2-O)- and -(Si(Me)(-(CH2)q-NH2)-O)- constitute (100-z)% and z% respectively, expressed in mol%, of the polymer chain (2a) excluding the terminal -SiMes groups, z is at least 2 mol% and at most 40 mol%, preferably at least 4 mol% and at most 30 mol%, more preferably at least 5 mol% and at most 10 mol%, z being defined by the following equation: [Math. 1]

[0021] In the composition according to the present invention, preferably the number of amine groups (-NH2) per polymer chain (2a), y2, is between at least 10 and at most 80, preferably between at least 20 and at most 60.

[0022] In the composition according to the present invention, preferably the number of urea groups (-(NH(C=O))-NH-L2) per polymer chain (2), y3, is between at least 10 and at most 80, preferably between at least 20 and at most 60.

[0023] In the composition according to the present invention, preferably the polymer (2a) comprises between at least 10 and at most 80 amine groups (-NH2) per chain, preferably between at least 20 and at most 60 amine groups (-NH2) per chain.

[0024] In the composition according to the present invention, preferably the compound (E) comprising a single isocyanate group (-N=C=O) is selected from alkyl monoisocyanates, aromatic monoisocyanates, alicyclic monoisocyanates, or alkyl carbonyl monoisocyanates, or phenyl carbonyl monoisocyanates, or alkoxy carbonyl monoisocyanates, or phenoxy carbonyl monoisocyanates, or fluorenylmethoxy carbonyl monoisocyanates.

[0025] In the composition according to the present invention, preferably L2 is chosen from the following groups, the symbol * indicating a carbon atom that is part of the L2 structure and is also a branch point: (L2-1) [Chem. 21] (L2-2) [Chem. 22] (L2-3) [Chem. 23] (L2-4) [Chem. 24] (L2-5) [Chem. 25] .

[0026] In the composition according to the present invention, preferably the sum of the masses of polymers (1) and (2) being taken as 100% by weight (without taking into account various additives and solvents), the quantity of polymer (2) in the mixture (1) + (2) is at least 1% by weight and at most 99% by weight, more preferably at least 10% by weight and at most 70% by weight, even more preferably at least 20% by weight and at most 80% by weight, particularly preferably at least 30% by weight and at most 50% by weight, and in a very preferred embodiment at least 35% by weight and at most 45% by weight.

[0027] In another aspect of the present invention, it relates to the use of a composition as defined above in adhesive products intended for application to skin, wounds, skin appendages, and / or mucous membranes. The present invention also relates to a dressing comprising an elastomeric matrix obtained from the composition of the invention as defined above. In the dressing according to the invention, the elastomeric matrix may have through holes. In the dressing according to the invention, the elastomeric matrix may further contain one or more active ingredients for wound treatment, the active ingredients being selected from the group consisting of: antibacterials, antiseptics, analgesics, anti-inflammatories, wound-healing agents, and anesthetics. In the In the dressing according to the invention, the elastomeric matrix may be present in the form of an adhesive border allowing the dressing to be fixed to the skin surrounding a wound to be treated. In the dressing according to the invention, the elastomeric matrix may be present in the form of a film having a thickness of at least 20 µm and at most 50 µm.

[0028] In another aspect of the present invention, it relates to a polymer of formula (F): [Chem. 28] - yl and y 2 represent integers greater than or equal to 2; - y3 represents an integer between 1 and y2; it being understood that the amine and urea side groups can be found independently of each other along the PDMS polymer chain, - R3 represents a hydrocarbon group which can be saturated, linear or branched, and which contains between at least 1 and at most 6 carbon atoms, preferably between at least 2 and at most 4 carbon atoms, more preferably 3 carbon atoms, or R3 can be -(CH2)3-NH-(CH2)2-; and - L2 represents a saturated hydrocarbon group, linear or branched, cyclic or acyclic, or an unsaturated hydrocarbon group, linear or branched, comprising at least one double bond and / or at least one aromatic ring; a saturated hydrocarbon group, linear or branched, cyclic or acyclic, in which one or several CH2s have been replaced by O or C=O; or an unsaturated hydrocarbon group, linear or branched, comprising at least one double bond and / or at least one aromatic ring and in which one or more CH2s have possibly been replaced by O or C=O.

[0029] In the polymer according to the invention, preferably R3 can be chosen from the following groups, the symbol * indicating a branch point: (Rl-1) [Chem. (Rl-2) [Chem. 30] * _ CH2-CH2-CH2-NH-CH2-CH2-

[0030] The polymer according to the invention preferably has a number average molecular weight Mn of at least 10 kg / mol and at most 80 kg / mol, preferably of at least 20 kg / mol and at most 70 kg / mol, and more preferably of at least 40 kg / mol and at most 60 kg / mol.

[0031] In the polymer according to the invention, preferably, the groups -(Si(Me)2- O)- and -(Si(Me)(-(CH2)q-NH2)-O)- constitute (100-z)% and z% respectively, expressed in mol%, of the polymer chain excluding the terminal -SiMes groups, z is at least 2 mol% and at most 40 mol%, preferably at least 4 mol% and at most 30 mol%, more preferably at least 5 mol% and at most 10 mol%, z being defined by the following equation: [Math.

[0032] The polymer according to the invention preferably comprises between at least 10 and at most 80 lateral branch groups -R3-NH- per chain, preferably between at least 20 and at most 60 groups per chain.

[0033] In the polymer according to the invention, preferably, L2 is chosen from the following groups, the symbol * indicating a carbon atom that is part of the L2 structure and is also a branch point: Brief description of the drawings

[0034] [Fig. 1] Figure 1 shows examples of diisocyanates used for chain extension of a polydimethylsiloxane (PDMS) (polymer la) having terminal amine groups -NH2 or -NHR, R being a methyl or ethyl group.

[0035] [Fig. 2] Figure 2 shows examples of monoisocyanates used to prepare PDMS with hanging ureas (polymer 2).

[0036] [Fig. 3] Figure 3 shows the structure of a prepolymer with urea and ethyl urea functions as well as isocyanate terminations.

[0037] [Fig. 4] Figure 4 shows the structure of a prepolymer with urea and urethane functions as well as isocyanate terminations.

[0038] [Fig. 5] Figure 5 presents a G'20°c = f(Tec) diagram of ethylated materials.

[0039] [Fig. 6] Figure 6 presents a conceptual link between crosslinking and the presence of defects on adhesion properties.

[0040] [Fig. 7] Figure 7 shows an NMR spectrum 1 H of a PDMS to benzyl urea during in the THF.

[0041] [Fig. 8] Figure 8 shows the measurement of viscosity as a function of shear rate.

[0042] [Fig. 9] Figure 9 shows the DSC measurement of the different PDMS with hanging ureas. The five curves represent, in ascending order, the results observed for products Ad, Fmoc, Bz, Ci4 and Et, respectively.

[0043] [Fig. 10] Figure 10 illustrates the design of new systems (new compositions according to the present invention) with improved adhesion.

[0044] [Fig. 11] Figure 11 is a G'20°c = f(Tec) diagram of ethylated materials and mixtures between 5-MDI-50 and 20-PDMS-u-Bz.

[0045] [Fig. 12] Figure 12 is a G'20°c = f(Tec) diagram of mixtures between 5-MDI-50 or 3-MDI-30 and 20-PDMS-u-Bz.

[0046] [Fig. 13] Figure 13 is a graph representing the G'20°c and Téc of mixtures between 20-MDI-172 and 20-PDMS-u-Bz at different mass percentages.

[0047] [Fig. 14] Figure 14 is a G'20°c = f(Tec) diagram of mixtures between 20-PDMS-u-Bz and either 20-MDI-172, or 5-MDI-50 or 3-MDI-30.

[0048] [Fig. 15] Figure 15 shows the chemical structure of the mixtures of the promising system (preferred compositions).

[0049] [Fig. 16] Figure 16 presents a G'20°c = f(Tec) diagram of mixtures between 20-PDMS-u-Bz and 20-MDI-172 (top line) and between 50-PDMS-u-Bz and 50-MDI-172 (bottom line).

[0050] [Fig. 17] Figure 17 is a graph representing the G'20°c and Téc of the mixtures between the 20-MDI-172 and 50-PDMS-uY mixtures.

[0051] [Fig. 18] Figure 18 is a Time-Temperature superposition at 40 °C of the 20-MDI-172 system.

[0052] [Fig. 19] Figure 19 presents a creep-recovery experiment for 20-MDI-172.

[0053] [Fig. 20] Figure 20 presents standardized relaxation tests for 20-MDI-172 at 20, 40, 60 and 80 °C.

[0054] [Fig. 21] Figure 21 shows a tack measurement of the chemically crosslinked reference product (“Ref. urgo”), intrachain urea PDMS and mixtures with pendant benzyl-urea PDMS at 20, 30 and 40%.

[0055] [Fig. 22] Figure 22 presented a tack measurement of the chemically crosslinked reference product (“Ref. URGO”), sample M-40-Bz and mixture 5-MDI-50+ 20-PDMS-u-Bz. Description of the implementation methods

[0056] The present invention relates to the development of physically crosslinked polydimethylsiloxane (PDMS) materials through supramolecular interactions (hydrogen bonds, nn stacking, Van der Waals interactions, etc.). Specifically targeted are materials that behave like crosslinked polymers below approximately 100 °C and like a thermoplastic at temperatures between 100 and 150 °C; in other words, thermoplastic elastomers.

[0057] An objective of the present invention was to develop a material that closely resembles, in terms of mechanical properties and adhesion, chemically crosslinked PDMS currently used in dressings. It is desirable to obtain materials with high flow temperatures (Tec>100 °C) while having storage moduli at 20 °C below 100 kPa.

[0058] Materials based on two-component formulations (PMDS with intrachain urea + PDMS with pendant urea) according to the present invention offer significant ease of manufacture. In particular, these new systems can be reshaped at high temperatures using hot-melt processes, similar to hot-melt adhesives. They can be used in extrusion, mold-casting, solvent casting, and other processes. Once their shape is fixed at room temperature, they can be reshaped a second time to dimensions suitable for a new device. This is the advantage of the reversibility of their liquid-solid transition. Thus, it is even possible to "recycle" material scraps from the initial shaping. None of this is feasible with the chemically crosslinked systems currently in use.For these, any shaping is final. By simply adjusting the mass ratio of the two components of the two-component formulations (PMDS with intrachain urea + PDMS with pendant urea), a wide range of physicochemical properties is accessible (i.e., room temperature moduli, high temperature viscosity and adhesion).

[0059] The preservation modulus is a temperature-dependent property, and controlling its value is important during both the manufacturing and use phases. It is desired to be around 100 kPa at room temperature, i.e., during the use phase, to correspond to the usual mechanical properties of dressings, and to be as low as possible during the manufacturing phase to facilitate reshaping.

[0060] Regarding the flow temperature, it defines the temperature at which the material can be shaped in a hot-melt bonding process. But it also defines the high temperature at which the dressing device will no longer be stable (during storage or use).

[0061] Similarly, a significant tack is desirable during the room temperature use phase, but it is preferable for it to be low when hot, during the shaping phase to limit potential problems of excessive adhesion to the devices used in this context.

[0062] Regarding the important parameters during the use phase (as a dressing), it can generally be noted that it is advisable to optimize a value for the preservation modulus at 20°C (G'20°C) and a value for the tack at 20°C. For the manufacturing phase, an important parameter to consider is the flow temperature, Tec.

[0063] Another desirable characteristic for these systems concerns the adhesion of the resulting polymers. It is desirable to obtain adhesion properties approaching those of chemically crosslinked systems. Indeed, for chemically crosslinked systems, "tack" is generally linked to the presence of defects and dangling chains between crosslinking nodes. Intrachain PDMS urea polymers (polymer (1) in the compositions according to the present invention) alone do not provide sufficient adhesion.

[0064] < Elastomeric Matrix>

[0065] In one aspect, the present invention relates to an elastomeric matrix obtained from the compositions according to the invention as described above. In particular, the elastomeric matrix can be obtained by hot physical transformation using methods well known to those skilled in the art.

[0066] The elastomeric matrices thus obtained can be used in various devices, such as dressings. For dressing purposes, the matrix according to the invention will preferably be formed as a thin layer.

[0067] According to a preferred embodiment of the invention, the matrix has through holes. The through holes can be made by perforation or by punching the matrix previously formed in a thin layer.

[0068] Alternatively, matrices according to the invention can be manufactured by hot bonding of a polymeric composition as described above onto a plate engraved with the pattern selected to form through holes, followed by a cooling step and finally a demolding step.

[0069] The production of adhesive dressings generally involves complex specifications to reconcile conflicting characteristics. The main criteria for such a dressing are essentially good breathability while preventing leaks, and impermeability to liquids and bacteria while remaining breathable (i.e., permeable to water vapor). Ideally, the dressing should maintain its cohesion when removed once saturated with exudate, and should be easy to manufacture. The dressing must also be easy to apply and remain in place as long as possible without damaging the surrounding skin. Ideally, it should not interfere with wound healing upon removal. Finally, the dressing should conform to the patient's anatomy.

[0070] The elastomeric matrix is ​​preferably thin, so as to better conform to the body's shape and follow its movements without risk of detachment. The adhesive backing is advantageously conformable. Generally, elastomeric matrices according to the invention have a thickness between 15 µm and 2 mm.

[0071] The elastomeric matrix will preferably be impermeable to external fluids and pathogenic microorganisms while ensuring water vapor permeability, so as to avoid both contact of the wound with external liquids and bacteria and maceration of the wound.

[0072] The elastomeric matrix is ​​preferably adhesive in order to keep the dressing in place.

[0073] The matrix may contain active ingredients that play a beneficial role in wound treatment. Examples of substances that may be used as active ingredients in the context of the present invention include: - antibacterials such as silver derivatives like silver salts or other metals (e.g. silver sulfate, chloride or nitrate and silver sulfadiazine), silver complexes or other metals (e.g. silver zeolites such as alphasan, or ceramics), metronidazole, neomycin, polymyxin B, penicillins (amoxicillin), clavulanic acid, tetracyclines, minocycline, chlorotetracycline, aminoglycosides, amikacin, gentamicin or probiotics; - antiseptics such as chlorhexidine, triclosan, biguanide, hexamidine, thymol, Lugol's solution, povidone-iodine, benzalkonium chloride and benzethonium chloride; - painkillers such as Paracetamol, Codeine, Dextropropoxyphene, Tramadol, Morphine and its derivatives, Corticosteroids and derivatives; - anti-inflammatory drugs such as Glucocorticoids, non-steroidal anti-inflammatory drugs, Aspirin, Ibuprofen, Ketoprofen, Flurbiprofen, Diclofenac, Aceclofenac, Ketorolac, Meloxicam, Piroxicam, Tenoxicam, Naproxen, Indomethacin, Naproxcinod, Nimesulide, Celecoxib, Etoricoxib, Parecoxib, Rofecoxib, Valdecoxib, Phenylbutazone, Niflumic acid, Mefenamic acid; - active ingredients that promote healing, such as Retinol and Vitamin A, Vitamin E, N-acetylhydroxyproline, Centella Asiatica extracts, papain, essential oils of thyme, niaouli, rosemary and sage, hyaluronic acid, polysulfated oligosaccharides and their salts (especially synthetic sulfated oligosaccharides having 1 to 4 sugar units such as potassium salt of sucrose octasulfate or silver salt of sucrose octasulfate), sucralfate, allantoin, urea, metformin, enzymes (e.g. proteolytics such as streptokinase, tripsin or collagenase), peptides or protease inhibitors; - anesthetics such as benzocaine, lidocaine, dibucaine, pramoxine hydrochloride, bupivacaine, mepivacaine, prilocaine, or etidocaine.

[0074] Within the framework of the present invention, it is possible to envisage matrices that are easy to handle, are repositionable, allow for painless removal when applied to the skin, mucous membranes or hair, and have a satisfactory hold over time.

[0075] < Dressings>

[0076] The present invention also relates to a dressing comprising the elastomeric matrix obtained from compositions according to the invention.

[0077] According to a preferred embodiment of the invention, the present application relates to an absorbent dressing comprising an elastomeric matrix in the form of an adhesive border that can take the form of a "sidewalk," and which allows the dressing to be fixed to the skin surrounding the wound. These dressings, particularly when used for the treatment of especially painful chronic wounds, are advantageously conformable and thin in order to limit the tension that the dressing can generate on the skin surface. According to a preferred embodiment of the invention, the adhesive absorbent dressing comprises the assembly of an absorbent layer and the elastomeric matrix forming the sidewalk. absorbent dressing, which is respectful of the fragile and sensitive peri-lesional skin.

[0078] According to a preferred embodiment of the invention, the present application relates to an absorbent dressing comprising an absorbent layer coated with an elastomeric matrix in the form of a perforated coating. The through holes allow exudate to pass through to the absorbent layer. The elastomeric matrix covers the entire surface of the dressing in contact with the skin. Advantageously, this type of dressing does not adhere to moist wounds but adheres to the peri-wound skin, thus allowing for removal without trauma or pain. Among known dressings of this type, the products marketed by the Mölnlycke company under the Mepilex® brand can be cited.

[0079] According to a preferred embodiment of the invention, the present application aims to cover a self-supporting interface dressing comprising an elastomeric matrix in the form of a thin layer with perforated holes to allow exudate to pass through. The thickness of such a dressing is preferably between 0.4 and 2 mm. In order to protect the matrix from the external environment, the interface dressing may be covered, preferably on each of its faces, by a temporary protective film which will be removed by the user before use. Among known dressings of this type, the products marketed by URGO Laboratories under the UrgoTuI® brand may be cited.

[0080] According to a preferred embodiment of the invention, the present invention aims to cover a dressing composed of an elastomeric matrix in the form of a thin, transparent, adhesive film. The thickness of such a dressing is preferably between 20 and 50 µm. The transparency allows visual control of the area to be treated. These films are semi-permeable; they are permeable to gas exchange and impermeable to liquids and bacteria. They provide mechanical protection against the phenomena of friction, rubbing and shearing. Among the well-known dressings of this type, the products marketed by Smith & Nephew under the brand name Opsite®, or by 3M under the brand name Tegaderm® or by URGO Laboratories under the brand name Optiskin®, can be mentioned.

[0081] According to a preferred embodiment of the invention, the present invention aims to cover a dressing composed of an elastomeric matrix in the form of a flexible gel sheet. These dressings, particularly when used in the treatment of hypertrophic or keloid scars, are advantageously self-adhesive and conformable in order to adapt to each scar. Among known dressings of this type, the products marketed by Smith & Nephew under the Cica-care® brand can be cited.

[0082] In the present invention, the term "dressing" refers to any medical device of the dressing type comprising at least one elastomeric matrix. In particular, the invention applies to dressings used for wound treatment, scar treatment and cosmetic patches.

[0083] <Examples>

[0084] <1. Materials and methods>

[0085] <1.1 Polymers used>

[0086] <1.1.1 PDMS used>

[0087] The PDMS used were purchased from Gelest.

[0088] Three PDMS terminated with amine functions, denoted PDMSNHz, of the following structure (aminopropyl-terminated PDMS, PDMS NHZ): [Chem. 38] The following were used: DMS-A15 (3210 g / mol), DMS-A21 (5200 g / mol), and DMS-A31 (approximately 20,000 g / mol). The exact molar masses of the different batches were calculated by NMR. 1 H in deuterated chloroform.

[0089] A PDMS (DMS-A214), terminated with an ethyl amine function denoted PDMSNH, and of the following structure: [Chem. 39] was also used (approximately 2400 g / mol). Its exact molar mass was also calculated by NMR. 1 H in deuterated chloroform.

[0090] Two PDMS with pendant amine functions (branched amine PDMS, PDMSNHZ Branch) were also used, having the following structure: [Chem. 40]

[0091] These PDMSNHZ Branch included: AMS-1203 (20,000 g / mol; 20 mol% of branched amine monomer) and AMS-163 (50,000 g / mol; 7 mol% of branched amine monomer).

[0092] <1.1.2 Other products used>

[0093] To achieve chain extension of a polydimethylsiloxane (PDMS) (polymer α) containing amine terminal groups -NH2 or -NHR, where R is a methyl or ethyl group, four different diisocyanates were used: hexamethylene diisocyanate (HDI), isophorone diisocyanate Tl (IPDI) and 4,4'-methylene bis(cyclohexyl isocyanate) (HMDI), 4,4'-Methylene bis(phenyl isocyanate) (MDI) (Figure 1). Two diisocyanates from the same family as hexamethylene (HDI), butylene diisocyanate (BDI) and dodeca methylene diisocyanate (DDI), with 4 and 12 carbons, respectively, were also used.

[0094] To prepare PDMS with hanging ureas (polymer 2), different monoisocyanates were also used: namely benzyl isocyanate (Bz), ethyl isocyanate (Et), tetradecyl isocyanate (Cw), adamantyl isocyanate (Ad) and N-(9-fluorenylmethoxycarbonyl) isocyanate (Fmoc) (Figure 2).

[0095] <1.2 Polymerizations and modifications of polymers>

[0096] <1.2.1 Preparation of prepolymers, PDMS with intrachain ureas>

[0097] Prepolymers in the form of PDMS blocks decorated with intrachain urea groups were prepared by reaction with diisocyanates. To avoid thermal degradation, the reaction was carried out at room temperature in tetrahydrofuran (THF). For this purpose, one or two PDMS blocks terminated with amines or hydroxyl groups (approximately 10 g of PDMS in total) were placed in a 250 mL round-bottom flask in approximately 70 mL of THF under magnetic stirring. A solution of diisocyanate (volume measured using a micropipette) and THF (50 / 50 v / v) was then added dropwise, and the reaction mixture was stirred for 24 hours. Excess ethanol was then added to neutralize any remaining isocyanate functionality as urethane. The solvents were then removed by evaporation.

[0098] Table 1 shows the quantities of material used for the synthesis of each polymer, with the following nomenclature: AA-BBB-CCC where AA represents the nature and length of the PDMS chain (either amine-terminated with a molar mass of approximately 5 kg / mol (AA then being marked "5"), or ethyl amine-terminated (Et) with a molar mass of approximately 3 kg / mol (AA then being marked "3kEt"), or terminated hydroxyl (OH) with a molar mass of approximately 5 kg / mol (AA then being marked "5kOH")), BBB represents the nature of the isocyanate used, HD for the diisocyanate hexamethylene, IPD for isophorone diisocyanate and HMD for 4,4'-methylene bis(cyclohexyl isocyanate), and CCC the target molar mass for the different polymers (between 30 kg / mol and 172 kg / mol).

[0099] [Table 1] Amounts of substance of reactants and theoretical molar masses of the synthesized polymers

[0100] <1.2.2 Preparation of PDMS with hanging ureas>

[0101] For the preparation of PDMS with hanging ureas, a PDMS with hanging amines was dissolved in a THF solution, and then a monoisocyanate / THF solution (1:1 v / v) was added dropwise and the mixture was stirred magnetically for 24 hours. The solvent was then removed by evaporation. Table 2 shows the different quantities of material used for the synthesis of the prepared PDMS.

[0102] To calculate the amount of isocyanate to add, the minimum quantity of amine units per chain, according to supplier data, had to be determined.

[0103] For this purpose, the molar percentage of monomer-amine units is used to calculate the ratio of non-amine units to amine units, denoted X: [Math.

[0104] If we then consider the molar mass of a repeating motif "X non-amine units and 1 amine unit", it is possible to calculate the number of amines per chain (denoted A) by dividing the total molar mass of PDMS by the molar mass of the repeating motif: [Math.

[0105] Thus, 1 equivalent of PDMS is equal to A equivalents of amines. The value of A is approximately 40 for AMS-163 (50,000 g / mol; 6 mol% branched amine monomer) according to supplier data (knowing that these values ​​are not the same from one batch to another). As for the value of AMS-1203 (20,000 g / mol; 20% branched amine monomer), it is approximately 50.

[0106] Table 2 presents the different PDMS prepared and the associated quantities of materials. In the polymer names indicated, u-Bz, u-ET, u-Cw, u-Ad and u-Fmoc indicate, in their order of appearance in Figure 2, the lateral urea groups obtained by reaction with benzyl, ethyl, tetradecyl, adamanatyl and N-(9-fluorenylmethoxycarbonyl) isocyanates.

[0107] [Table 2] Amounts of substance of reactants and theoretical molar masses of the synthesized polymers Mass Quantity Mass Quantity 50-PDMS-ü-Ad 5 3.1 534 4 5B-PDMS-ü-Fmoc 5 9,1 1638 4

[0108] <1.2.3 PDMS Mixture>

[0109] The mixing protocol for PDMS with intrachain ureas and PDMS with pendant ureas was carried out by weighing the desired masses of each PDMS and dissolving them in a THF solution to obtain a homogeneous solution, then evaporating the solvent to obtain the final material. Due to the small quantities involved, this method was preferred. However, it would be possible to replace this process with high-temperature extrusion mixing.

[0110] <1.3 Characterization methods used>

[0111] <1.3.1 Nuclear Magnetic Resonance (NMR)>

[0112] The NMR was performed using the Bruker Avance 400 MHz spectrometer.

[0113] For PDMS, the NMR 1 H was carried out in deuterated chloroform or deuterated THF at 25 °C.

[0114] <1.3.2 Differential Scanning Calorimetry (DSC)>

[0115] Thermogram acquisition was performed using the TA Instruments DSC Q100 instrument equipped with a liquid nitrogen cooling system. 10 mg (+ / - 1 mg) of sample were introduced into aluminum crucibles and analyzed according to the following protocol: - Temperature ramp 10 °C / min up to 150 °C - Isothermal 1 min at 150 °C. - Temperature ramp 10 °C / min down to -150 °C - Isothermal 1 min at 0 °C. - 2 ème heating: 5 °C / min up to 150 °C.

[0116] The first heating cycle erases the thermal history of the materials. Thus, the characteristic temperatures of the materials are measured during the second heating cycle.

[0117] <1.3.3 Rheology>

[0118] Rheological measurements were performed using an Anton Paar MCR rheometer. A plane-plane geometry (diameter 0 = 8 mm) was used.

[0119] < Temperature Scanning>

[0120] The measurement of the storage and loss modules, G' and G", as a function of temperature was carried out as a function of temperature at a constant shear rate (y = 0.05%) and at an angular frequency of 10 rad / s.

[0121] The following protocol was used to perform the measurements: - Isothermal 1 min at 150 °C. - Temperature ramp 5 °C / min down to 0 °C. - Isothermal for 2 minutes at 0 °C. - 2 ème heating: 5 °C / min up to 150 °C.

[0122] < Frequency scan >

[0123] The following protocol was used to perform the measurements: - Frequency sweep (Isothermal at 20 °C). - Isotherm at 40 °C for 5 min, frequency sweep (Isotherm at 40 °C). - Isotherm at 60 °C for 5 min, frequency sweep (Isotherm at 60 °C). - Isotherm at 80 °C for 5 min, frequency sweep (Isotherm at 80 °C).

[0124] < Creep>

[0125] Creep-recovery measurements were also performed. For this, a stress of 500 Pa was applied for 250 s. After the stress returned to 0 Pa, the deformation evolution was recorded for 400 s to study the recovery phenomenon. The measurements were carried out at 20 °C and 40 °C.

[0126] <Relaxation of constraint>

[0127] Stress relaxation measurements were also performed by subjecting the samples to a strain E = 1% for 60 seconds. The measurements were taken at 20, 40, 60, and 80 °C.

[0128] <Tack>

[0129] Tack tests were also carried out by placing a 1 mm thick material between the two geometries of the rheometer, at 40 °C, and then following the following protocol: - The high geometry compresses the sample at 16 pm / s for 30 seconds. - The high geometry is held in place for 30 seconds. - The upper geometry is removed rapidly at 1 mm / s.

[0130] The evolution of normal force is studied throughout the test.

[0131] <2. Results>

[0132] <2.1 Studies of linear intrachain PDMS-ureas>

[0133] Intrachain PDMS-urea materials were prepared at room temperature by performing solvent syntheses in THF, as described in the "Materials and Methods" section.

[0134] The results relating to this work are summarized below.

[0135] In this study, the influence of three parameters was investigated: - The nature of the diisocyanate (HD vs HMD vs IPD vs MDI); - The molar mass of PDMSNHZ used for the synthesis of intrachain PDMS-ureas; - The nature of the intrachain polar functions (urea vs ethyl urea vs urethane).

[0136] The impact of the different parameters was studied by analyzing the rheological behavior of the materials using temperature sweeps. The main results, in terms of Tec and storage modulus at 20 °C (denoted G' (20 °C)), are presented in Table 3.

[0137] [Table 3] Tec and G' at 20 °C of the synthesized materials Polymer Mo inlet T^- C) G' (20 °C) (kPa)

[0138] <2.1.1 Influence of the nature of the diisocyanate>

[0139] Entries 1, 2, 3, and 6 in Table 3 show the evolution of Tec and G' (20 °C) for intrachain PDMS-ureas with a molar mass of approximately 50 kg / mol obtained from 5 kg / mol PDMS-NHZ with different diisocyanates: i.e., 5-X-50 or X = HD, IPD, HMD, or MDI. Clearly, Tec and G' (20 °C) are strongly influenced by the nature of the diisocyanate. 5-IPD-50 (entry 2) exhibits the The lowest Tec and G' (20 °C) values ​​were observed. Without limiting ourselves to a single possible interpretation, it is postulated that this effect is linked to the steric hindrance of the IPD isophorone motif and its asymmetry, which disrupt the self-organization of the chains and thus the formation of the urea-urea hydrogen bond network. Conversely, 5-MDI-50 (entry 6) exhibited the highest Tec and G' (20 °C) values. It is postulated that the two aromatic rings of the MDI methyl diphenyl motif can establish nn interactions that add to the urea-urea hydrogen bond network and strengthen the interchain bonds. The use of diisocyanates or diisocyanate mixtures is therefore crucial for controlling Tec and G' (20 °C).Furthermore, it is observed that only the MDI-based polymer has a flow temperature exceeding 100 °C, which is a significant advantage in the industrial preparation of compositions and dressings within the context of the present invention. Thus, MDI diisocyanate (4,4'-Methylenebis(phenyl isocyanate)) is considered particularly advantageous in the preparation of linear intrachain PDMS ureas used in the compositions of the present invention.

[0140] <2.1.2 Influence of the molar mass of PDMS-SNHZ used for the synthesis of intrachain PDMS-ureas>

[0141] Entries 4, 5, and 6 in Table 3 show the evolution of Tec and G' (20 °C) for intrachain PDMS-ureas obtained from MDI and PDMSNH2 with different molar masses: 3 kg / mol (entry 4), 20 kg / mol (entry 5), and 5 kg / mol (entry 6). Clearly, the lower the molar mass of PDMSNH2, the higher G' (20 °C), in other words, the "harder" (or more elastic) the material. Without limiting ourselves to a single possible interpretation, it is postulated that, considering that a decrease in the molar mass of PDMSNH2 is accompanied by an increase in the urea bond density along the chain, this results in a denser urea-urea hydrogen bond network, and therefore a higher degree of physical crosslinking. Conversely, Tec increases at As the molar mass of PDMSNH2 increases, this seems counterintuitive. However, it is important to consider that an increase in the molar mass of PDMSNH2 is accompanied by a significant increase in the molar mass of intrachain PDMS urea (from 30 kg / mol for PDMSNH2 = 3 kg / mol (entry 4), to 172 kg / mol for PDMSNH2 = 20 kg / mol (entry 6)). As the molar mass of intrachain PDMS urea increases, the entanglement rate also increases. Tec is strongly influenced by the entanglement rate and is an increasing function of this parameter.

[0142] <2.1.3 Influence of the nature of intrachain polar functions>

[0143] Entries 7 to 11 in Table 3 show the evolution of Tec and G' (20 °C) for intrachain PDMS-ureas obtained by reacting MDI with a mixture of NH2-terminated PDMS, PDMSNH2 (M n = 5 kg / mol) and of NH-ethylated PDMS, PDMSNH, Et(M n(= 3 kg / mol). The chemical formula of the resulting polymer is shown in Figure 3. They are denoted 5 / 3kEt-MDI-50 (X / (100-X)), where X is the mass percentage of PDMSNH2 used. As X decreases, the proportion of ethyl urea increases, and the Tec and G' (20 °C) decrease. It appears that ethylation inhibits the formation of hydrogen bonds and therefore reduces the apparent degree of physical crosslinking.

[0144] Entries 12 to 16, meanwhile, show the evolution of Tec and G' (20 °C) for intrachain PDMS-ureas / urethanes obtained by reaction of MDI with a mixture of terminating PDMS NH2, PDMSNH2 (M n = 5 kg / mol) and PDMS terminated OH, PDMSOH (M n(= 5 kg / mol). The chemical formula of the resulting polymer is shown in Figure 4. They are denoted 5 / 3kOH-MDI-50 (Y / (100- Y)), where Y is the mass percentage of PDMSNH2 used. As before, the lower Y, the higher the proportion of urethane, and the lower Tec and G' (20 °C). Without limiting ourselves to a single possible interpretation, it is postulated that urea-urethane or urethane-urethane interactions lead to weaker hydrogen bonds than urea-urea interactions. The resulting physical network would therefore be less cohesive. It should be noted that the materials prepared with 100% ethyl ureas (i.e. 3kEt-MDI-50) and 100% urethanes (i.e. 3kOH-MDI-50) are viscous liquids at room temperature.

[0145] Ethylation of ureas or their substitution with urethane groups is therefore another effective strategy for modulating Tec and G' (20 °C). However, it seems difficult to design materials with a low modulus (G' (20 °C) ~ 100 kPa) while maintaining a high flow temperature (Tec ~ 100 °C) using this strategy. Figure 5 shows the G'20 °C = f(Tec) diagram for the ethylated urea polymers 5 / 3kEt-MDI-50 (X / (100-X)). It can be seen that the modification of Tec (also denoted Tfl) OW ) perhaps finely controlled, but the effect on the storage module is limited. Following this work, it became apparent that a system needed to develop allowing a greater variation in G' (20 °C).

[0146] <2.2 PDMS with hanging ureas>

[0147] <2.2.1 Objectives>

[0148] As presented above, intrachain urea PDMS have enabled the development of a series of materials for which it is possible to finely control the rheological properties, G' (20 °C) and Tec, by playing on different parameters: the nature of the diisocyanate, the use of an ethyl amine PDMS.

[0149] However, it is difficult to design materials with a low modulus (G' (20 °C) ~ 100 kPa) while maintaining a high flow temperature (Tec ~ 100 °C).

[0150] On the other hand, another desirable characteristic for these systems concerns the adhesion of the resulting polymers. It is desirable to obtain adhesion properties approaching those of chemically crosslinked systems. Indeed, for chemically crosslinked systems, "tack" is generally linked to the presence of defects and dangling chains between the polymers. crosslinking nodes (Figure 7). However, the intrachain PDMS urea polymers described previously are likely devoid of them.

[0151] <2.2.2 Summary>

[0152] The following diagram shows a synthesis pathway for a pendant urea PDMS: [Chem. 41]

[0153] The synthesis is carried out according to the protocol described in the "Materials and Methods" section above. A PDMS with a pendant amine is reacted with a monoisocyanate in THF at room temperature. In a practical example, the PDMS used has a mass of 50,000 g / mol and 6 mol% of its repeating units contain an amine group. The monoisocyanates used are benzyl isocyanate (Bz), ethyl isocyanate (Et), tetradecyl isocyanate (CK), adamantyl isocyanate (Ad), and N-(9-fluorenylmethoxycarbonyl) isocyanate (Fmoc) (see Figure 2).

[0154] The resulting branched polymers are denoted X-PDMS-u-YY (where X is the molar mass of the commercial PDMS used, and YY = Bz, Et, Ci4, Ad, or Fmoc). For calculating the monoisocyanates to be added, supplier data was used to ensure that the same quantity of isocyanate was added regardless of the batch of the commercial product used. Therefore, a value of 6 mol% amine monomer units was used for the calculations.

[0155] However, after reaction, NMR analysis of the resulting polymers suggests that a significant fraction of the amine groups did not react, and therefore that the isocyanate is introduced in deficiency. For example, Figure 7 shows the spectrum NMR 1H of 50-PDMS-u-Bz. The signal of the α-protons of the amine groups can be distinguished from the signal of the α-protons of the urea groups. This indicates that amine groups are always present at the end of the reaction. Furthermore, the proton integrals allow us to calculate that approximately 65% ​​of the hanging amines have been transformed into hanging ureas.

[0156] This result allows us to estimate the actual level of suspended amines in commercial PDMS. It would actually be closer to 9 mol% (and not 6 mol% as stated by the supplier).

[0157] <2.2.3 Rheological and thermal properties>

[0158] Visually, the functionalization of PDMS with pendant amines and monoisocyanates results in an increase in viscosity, regardless of the specific monoisocyanate used. However, in all cases, the resulting polymer is a viscoelastic liquid (the "molten state"). The pendant ureas form hydrogen bonds responsible for the increased viscosity, but these bonds are insufficient to lead to the formation of a cohesive physical network, i.e., a viscoelastic solid.

[0159] Figure 8 shows the viscosity evolution of the different 50-PDMS-u-YY as a function of shear rate at 20 °C, as well as that of the starting PDMS with a pendant amine. In all cases, the 50-PDMS-u-YY exhibit a viscosity profile typical of a polymer in the melt state, with a Newtonian plateau, for shear rates between 0.1 and 10 s⁻¹. 1followed by a shear-thinning regime where viscosity decreases as shear rate increases. In this latter regime, the chains untangle and / or dissociate under the effect of shear.

[0160] For all PDMS with pendant urea, the viscosity in the Newtonian regime is much higher than that of the starting PDMS with pendant amine, by a factor of ~10 for 50-PDMS-u-Bz, 50-PDMS-u-Et and 50-PDMS-u-Ad and by a factor of ~50-100 for 50-PDMS-U-C14 and 50-PDMS-u-Fmoc. This increase The viscosity could be explained by inter-chain interactions related to hydrogen bonds established by the ureas. In the case of 50-PDMS-U-C14 and 50-PDMS-u-Fmoc, without limiting ourselves to a single possible interpretation, it is postulated that this increase is more significant because the fatty chains Ci and n-conjugated Fmoc will establish additional inter-chain interactions, of the Van der Waals and nn stacking type, respectively, which will add to the effect of the urea-urea hydrogen bonds.

[0161] The thermal transitions of PDMS with dangling urea were studied by DSC (Figure 9). Similar to PDMS with intrachain ureas, no transition appears to correspond to reversible urea-urea associations via hydrogen bonds. For all polymers, a glass transition temperature between -115 °C and -105 °C is observed, indicating that the addition of dangling ureas did not impact the glass transition temperature of these PDMS materials. Melting is observed in the case of 50-PDMS-U-C14 between -30 °C and 40 °C. This corresponds to the melting of the crystalline domains resulting from the crystallization of the long alkane chains.

[0162] Thus, these various analyses have shown that these different PDMS with dangling ureas possess increased cohesion compared to PDMS with dangling amines, without, however, affecting the glass transition temperature. This increased cohesion is explained by hydrogen bonds formed by the urea groups. These interactions can be strengthened through additional interactions such as Van der Waals interactions or nn stacking for 50-PDMS-U-C14 and 50-PDMS-u-Fmoc, respectively.

[0163] However, a limiting parameter of these systems is that they behave like viscous liquids at room temperature, and no longer like viscoelastic solids. To overcome this limitation, the two types of polymer, namely the intrachain urea system and the pendant urea system (polymers (1) and (2)), were used in a mixture in the present invention as shown in the diagram in Figure 10, the latter using as an illustration a diisocyanate particularly preferred in the context of the present invention, MDI (4,4'-diphenylmethylene diisocyanate).

[0164] <2.3 Mixture of PDMS with intrachain ureas and pendant ureas>

[0165] <2.3.1 Objective>

[0166] During the course of developing the present invention, it was observed that intrachain urea-based PDMS with flow temperatures within desirable ranges (Tec ~ 100 °C) exhibited excessively high elastic moduli at room temperature and lacked adhesive behavior. This behavior appeared to be partly due to the excessive regularity of the linear chains, which promotes excellent self-organization. Conversely, pendant urea-based PDMS were developed that behaved like viscoelastic liquids with high tack, but due to their molten state, they could not be used in dressing preparation applications. In order to combine the respective advantages of these two series of materials, while hoping to achieve the desired rheological behavior, it was decided to explore their use in mixtures, as shown in Figure 10.

[0167] These systems are highly modular because many parameters can be modified to adapt the thermal and rheological properties. These include both parameters relating to PDMS with intrachain ureas (e.g., molar mass of PDMS-NHZ, urea ethylation rate, etc.) and parameters relating to PDMS with pendant ureas (e.g., molar mass of the PDMS chain, grafting rate, nature of the pendant group, etc.).

[0168] <2.3.2 Impact of parameters relating to PDMS with intrachain ureas>

[0169] <2.3.2.1 Reference case: 5-MDI-50 + 20-PDMS-u-Bz>

[0170] For all the first mixing systems studied, the pendant urea PDMS used was 20-PDMS-u-Bz from the reaction of commercial pendant amine PDMS with a molar mass of 20,000 g / mol with 6 mol% of pendant amine units, with benzyl isocyanate (Bz) (see previous part).

[0171] First, 20-PDMS-u-Bz was combined in a mixture with intrachain urea PDMS 5-MDI-50, resulting from the reaction of 5 kg / mol PDMSNHZ with MDI.

[0172] 5-MDI-50 is mixed with 20-PDMS-u-Bz at different mass percentages: 80 wt., 60 wt., and 40 wt. The rheological properties of the resulting materials, G' (20 °C) and Tec, are reported in Table 4 (Entries 1 to 4). Note that it was not possible to study the mixtures with 20 wt. of 5-MDI-50 because the mixture obtained after solvent evaporation is not homogeneous. This suggests that, in these proportions, 5-MDI-50 and 20-PDMS-u-Bz demix.

[0173] [Table 4] Mass composition, Tec and G' at 20 °C of the different PDMS mixtures Entry Percentage nsassique *,. t PD S ureas of PDMS ureas T ic “ / P QMS ureas irstracname <.... L) pensive mtrac dwarf (in Q 1 5-MDLSD 20-PDMS-u-Bz 1 O 137 1250 2 5-MD(-30 20-PDMiS-u-S? SO 112 644 3 5-MD(-5D 20-PDMS-u-Sz 60 SS 655 4 5-MD450 20-PDMS-u-fiz 40 75 4OO 5 5 / 3kEt-MDi-5O (50 / 20) 20-PDMS-u-Bz 1OÜ 107 1040 6 5 / 3 k Et- MOi-SO (80 / 20) 20-PDMS-u-Bz 80 50 390 7 8 / 3 kEt-MDi-50 (50 / 20) 20-PDMS-u-Bz 60 45 153 8 5 / 3kEt-MDi-5û (50 / 20) 20-PDMS-u-Bz 40 35 74 9 3-MD(-3O 20-PDMS-u-Bz 100 114 3902 10 3-MDS-3O 20-PDMS-u-Bz 80 120 2507 11 3-MD(-30 20-PDMS-u-Bz 60 82 781 12 3-MD(-3O 20-PDMS-u-fiz 40 51 296 13 2O-MDM72 20-PDMS-u-Bz 100 150 232 14 2O-MDÊ-172 20-PDMS-u-Sz 80 142 99 15 20-MDM72 20-PDMS-u-Bz 60 150 76 16 2O-MD(-172 20-PDMS-u-Bz 40 129 58

[0174] Increasing the mass percentage of 20-PDMS-u-Bz results in a decrease in G' (20 °C) and Téc. Furthermore, the mixtures become increasingly adhesive as the proportion of PDMS-u-Bz increases. Laboratory tests have shown that the material 5-MDI-50 + 20-PDMS-u-Bz (60 / 40) can be used to bond a metal spatula to a piece of Teflon. The introduction of "disorder" in the physical gel therefore seems to allow us to approach the adhesive properties of chemically crosslinked systems.

[0175] Figure 11 shows the G'(20 °C) = f(Tec) diagram for all 5-MDI-50 + 20-PDMS-u-Bz systems (entries 1 to 4 in Table 4). It is compared to the equivalent diagram for intrachain urea PDMS polymers with different degrees of ethylation, 5 / 3kEt-MDI-50(X, 1-X), where X is the percentage of unethylated urea (Table 3, entries 7 to 11). The introduction of 20-PDMS-u-Bz results in materials with lower moduli than the ethylated intrachain urea PDMS materials. However, the moduli remain relatively high (> 200 kPa). Although approaching the "target zone," further optimization of the material properties is still required before it can be achieved.

[0176] <2.3.2.2 Influence of PDMS urea ethylation intrachain>

[0177] PDMS-u-Bz was then combined in a mixture with a partially ethylated intrachain urea PDMS, 5 / 3kEt-MDI-50 (80, 20) (entry 8 of Table 3).

[0178] 5 / 3kEt-MDI-50 (80, 20) is mixed with 20-PDMS-u-Bz at different mass percentages: 80 wt%, 60 wt%, and 40 wt%. The rheological properties of the materials thus obtained, G' (20 °C) and Tec, are reported in Table 4 (Entries 5 to 8). Again, increasing the mass percentage of 20-PDMS-u-Bz results in a decrease in G' (20 °C) and Tec, even more pronounced than in the case of the non-ethylated systems described previously. Interestingly, it is even possible to achieve G' (20 °C) values ​​below 200 kPa (Entries 7 and 8), but then the Tec value becomes too low (< 50 °C).

[0179] <2.3.2.3 Influence of PDMS block size of intrachain PDMS urea>

[0180] To try to reach the target zone in terms of G' (20 °C) and Tec, two strategies were then considered: (i) the combination of 20-PDMS-u-Bz with an intrachain urea PDMS whose PDMS blocks are of low mass molar (< 5 kg / mol), (ii) or, conversely, of high molar mass (> 5 kg / mol). Both strategies can lead to an increase in Tec: by increasing the urea functional density (in the case of strategy (i)) or by increasing the total molar mass and therefore the degree of entanglement (in the case of strategy (ii)).

[0181] 20-PDMS-u-Bz was therefore first combined in a mixture with intrachain urea PDMS 3-MDI-30 (entries 9 to 12 in Table 3) using the same mass percentages as before (80 wt%, 60 wt%, and 40 wt%). The rheological properties of the materials thus obtained, G' (20 °C) and Tec, are reported in Table 4. Unfortunately, the rheological properties are very close to those of the materials from the 5-MDI-50 + 20-PDMS-u-Bz mixtures. The G' (20 °C) values ​​are even slightly higher, presumably due to the increased urea functional group density along the 3-MDI-30 chain. This trend is clearly shown in Figure 12 which represents the diagrams G' (20 °C) = f(Tec) for the two systems, 5-MDI-50 + 20-PDMS-u-Bz and 3-MDI-30 + 20- PDMS-u-Bz.

[0182] Finally, 20-PDMS-u-Bz was combined in a mixture with the intrachain urea PDMS 20-MDI-172 (entries 13 to 16 in Table 3, for mass percentages ranging from 80 wt%, 60 wt%, and 40 wt%). In this case, a clear decrease in the G' value (20 °C) was observed, falling below 100 kPa at 20 wt% wt% of 20-PDMS-u-Bz, while maintaining Tec values ​​above 100 °C. These results indicate that increasing the size of the PDMS blocks is a good strategy for reducing the modulus, while maintaining high transition temperatures due to chain entanglement.

[0183] Figure 13 shows the evolution of Tec and G' (20 °C) as a function of the mass percentage of PDMS-u-Bz introduced into the mixture. The dark areas represent the target value windows for Tec and G' (20 °C), respectively. It is clear that for a mass percentage of 40 wt% of 20-PDMS-u-Bz, the material meets the specifications. This is also clearly shown in Figure 14, which represents the G'(20 °C) = f(Tec) diagram. This diagram crosses the target zone.

[0184] The 20-MDI-172 + 20-PDMS-u-Bz system being very promising, this combination has been in detail, and those derived from it, notably by combining 20-MDI-172 with pendant urea PDMS of variable chemical nature.

[0185] <2.3.3 Rheological study of mixtures 20-MDI-172 + 50-PDMS-u-YY>

[0186] The section below focuses on the 20-MDI-172 + 50-PDMS-u-Bz system, as well as the 20-MDI-172 + 50-PDMS-u-YY systems (where YY = Bz, Et, Ci4, Ad or Fmoc) in order to assess the potential impact of grouping during.

[0187] As before, we consider 20-MDI-172 + 50-PDMS-u-Bz with mass concentrations of 50-PDMS-u-Bz of 20, 30 and 40%. For simplicity, they are denoted M-20-Bz, M-30-Bz, M-40-Bz, respectively.

[0188] To study the influence of the chemical nature of the pendant group, 20-MDI-172 was also mixed with 50-PDMS-u-Et, 50-PDMS-u-Ad, 50-PDMS-U-C14, 50-PDMS-u-Fmoc, and with the pendant amine PDMS used for the synthesis of 50-PDMS-u-YY. In each case, the same mass concentration of PDMS-u-YY was used: 30% by weight. These mixtures are designated M-30-Et, M-30-Ad, M-30-C14, M-30-Fmoc, and M-30-NH2, respectively.

[0189] All these mixtures were characterized through a set of five rheological tests: - A temperature scan (measurement of Tec and G' (20 °C)) - A frequency sweep (measurement of the angular frequency of crossover) - A creep test at 40°C (measurement of elastic recovery) - A stress relaxation test (measurement of relaxation times and the associated activation energy) - Tack tests at 37°C.

[0190] <2.3.3.1 Temperature Scanning>

[0191] All MX-YY samples were tested during a temperature sweep from 20 °C to 150 °C (φ = 10 rad / s). Table 5 shows the flow temperature, Tec, and the storage modulus at 20 °C, G' (20 °C), of the different mixtures.

[0192] < Influence of the mass fraction of 50-PDMS-u-Bz >

[0193] For the MX-Bz series (entries 2 to 4 in Table 5), increasing the mass fraction of the hanging urea PDMS, 50-PDMS-u-Bz, results in a significant drop in G' (20 °C) below 100 kPa, as specified. Tec decreases by approximately 20 °C across the entire series, a moderate drop that allows the flow temperature to remain above 100 °C (the minimum acceptable value) for the whole series. 50-PDMS-u-Bz introduces disorder and counteracts the linear self-organization of 20-MDI-172. The resulting materials exhibit a more heterogeneous physical crosslinking density, with very loosely cohesive areas that lead to an overall reduction in the macroscopic modulus of the materials. It is also likely that the introduction of 50-PDMS-u-Bz impacts the chain entanglement rate.Since the molar mass of 50-PDMS-u-Bz is lower than that of 20-MDI-172, the average entanglement rate should decrease, which may partly explain the decrease in Tec.

[0194] Comparing the 20-MDI-172 + 20-PDMS-u-Bz systems (described previously) with the 20-MDI-172 + 50-PDMS-u-Bz systems also provides important information; notably, the drop in temperature (Tec) is less significant for the 50-PDMS-u-Bz systems than for the 20-PDMS-u-Bz systems. (Figure 16). Indeed, the addition of 50-PDMS-u-Bz likely results in a smaller decrease in the average entanglement rate of the system.

[0195] <Influence of the nature of the grouping during 50-PDMS-u-YY>

[0196] For the M-30-YY series (entries 3 and 5 to 8 in Table 5), in all cases, the addition of 50-PDMS-u-YY again results in a significant drop in G' (20 °C) below 100 kPa. Similarly, a moderate drop in Tec is observed. The underlying physicochemical mechanisms are the same as those described above. Figure 17 shows the evolution of Tec and G' (20 °C) for all samples obtained with PDMS containing pendant urea. The use of different pendant urea groups does not appear to significantly affect the flow temperature and modulus of the different systems, with the exception of M-30-Fmoc, for which the flow temperature is slightly lower than for the rest of the series. This could be explained by better compatibility between 20-MDI-172 and 50-PDMS-u-Fmoc due to the aromatic nature of MDI and Fmoc. 50-PDMS-u-Fmoc would therefore be a better "diluting agent" for 20-MDI-172, which could notably result in a more pronounced reduction in the degree of entanglement between the 20-MDI-172 chains.

[0197] The case of the M-30-NH2 system (entry 9, Table 4) indicates that the combination of 20-MDI-172 with a PDMS decorated with a pendant amine group leads to a significantly greater decrease in G' (20 °C) and Tec compared to other 50-PDMS-u-YY additives. This result was expected because, in this case, the overall urea group density is greatly reduced (the additive being devoid of it). The physical crosslinking density of M-30-NH2 is therefore much lower. This control system indicates that the urea groups of the 50-PDMS-u-YY additives play an active role in modulating the rheological properties of the M-30-YY systems by contributing to the establishment of the hydrogen bond network.

[0198] [Table 5] Flow temperature and storage modulus at 20 °C of polymer blends Polymer inlet 1 2Ü-MDÎ-172 150 232 2 142 99 3 15Ü 75 4 129 38 5 13S 37 5 IBS 81 7 146 75 S 121 66 9 læ 47

[0199] Although these new systems exhibit flow temperatures exceeding 100 °C, these measurements were performed at a constant frequency and therefore do not necessarily represent the systems' behavior at very low frequencies, i.e., over long timescales. For all the samples presented here, their dimensions remain stable over time on timescales on the order of months. However, it is necessary to subject them to another battery of tests to predict the timescale over which they can flow and to what extent they can recover their initial shape after deformation under stress. The samples were therefore subjected to frequency sweep and creep tests.

[0200] <2.3.3.2 Frequency Scanning>

[0201] All MX-YY samples were tested during frequency sweeps from 0.1 rad / s to 10 rad / s at different temperatures (see Materials and Methods section). This allows the evolution of the storage and loss modulus, G' and G", to be plotted over a wide frequency range (from 0.005 rad / s to 100 rad / s) using the time-temperature equivalence. These curves are plotted for a reference temperature of 40 °C, i.e., the maximum storage temperature of the products.

[0202] Figure 18 shows the typical evolution of G' and G" as a function of œ, for the reference sample 20-MDI-172. It can be seen that the curves intersect at an angular crossover frequency, œ c , to which we associate an average relaxation time, T = 2n / œ cThis behavior is typical of a non-crosslinked polymer in its flow transition zone. It indicates that, under certain conditions, the polymer will flow at 40 °C. In simpler terms, stresses that occur on short timescales (i.e., ε > ε c or t < T) will induce a predominantly elastic response of the material. Conversely, processes that occur on longer time scales (i.e., œ < œ c or t > T) will induce a predominantly viscous response from the materials.

[0203] From a practical point of view, it is advantageous to obtain materials with the lowest possible angular frequency of crossing (conversely, the highest possible average relaxation time) to prevent the materials from flowing under the effect of their own weight (constant stress, therefore over a very long time).

[0204] In this study, the flow zone was investigated for all samples following the same protocol. Table 6 presents the angular frequency of crossover, œ c and the average relaxation time, T, of the different mixtures. The crossover modulus, G c , as well as the crossover viscosity, r| c defined as, are also provided.

[0205] [Table 6] Angular frequency, modulus and viscosity at the crossover point of polymer blends i-frequency time of,,,,,. fto angu,la.ire se re t laxation..ion Modal of Entry Viscosity poly,lymere average crossing T I. S, J crossing ' crossing, 2 M-2O-SS 0.0098 541 6855 4.4 x 10® 3 M-30-8s O. O175 359 6399 2.3 x 10® 4 M-4O-S. O58S 111 5555 6.15 x 1O 1 5 M-3O-EÏ O. O798 79 6300 4.96 x read 5 6 M-30-Ad 0.0276 228 7235 1.64 x read s7 M-30-C» 0.0397 158 7797 1.23 x 10' 8 M^SO-fmoc 0.0139 452 4163 188 x 10®

[0206] <Influence of the mass fraction of 50-PDMS-u-Bz>

[0207] For the MX-Bz series (entries 2 to 4 in Table 6), increasing the mass fraction of PDMS with hanging ureas, 50-PDMS-u-Bz, results in a progressive increase in œ c , and therefore a decrease in T. This expected trend again reflects the decrease in the degree of physical crosslinking (related to urea-urea hydrogen bonds and chain entanglements) as the mass fraction of 50-PDMS-u-Bz increases. On average, a factor of 10 is observed between the values ​​of the basic linear PDMS, 20-MDI-172, and the MX-Bz mixtures. It can therefore be predicted that the mixtures will flow approximately 10 times faster than 20-MDI-172. For the same reasons, G is observed c and q c decrease when the mass fraction of 50-PDMS-u-Bz increases.

[0208] <Influence of the nature of the grouping during 50-PDMS-u-YY>

[0209] For the M-30-YY series (entries 3 and 5 to 8 in Table 6), in all cases, the addition of 50-PDMS-u-YY again results in an increase in œ c , by a factor > 10, as well as a decrease in G c and r| c , again reflecting the fact that the mixtures will flow faster than 20-MDI-172. Overall, this trend is little impacted by the nature of the group during.

[0210] It should be noted that these measurements allow for comparison between samples and highlight an increased risk of spontaneous flow over very long periods in the case of mixtures. However, they do not allow for the precise prediction of the timescale at which a significant effect on sample dimensions will be observed. Thus, for all the samples tested in this study, no significant changes in their dimensions were noted.

[0211] In order to obtain more quantitative information in the event that the samples were deformed under the effect of an external stress, creep tests were subsequently carried out.

[0212] <2.3.3.3 Creep>

[0213] All MX-YY samples underwent creep testing, which involved subjecting the sample to a stress of 500 Pa for 250 s, followed by an observation of the recovery phenomenon for 400 s after the stress returned to 0 Pa. Each sample was tested at 20 °C and 40 °C, the estimated maximum storage temperature. A reference material (chemically crosslinked) was tested under the same conditions.

[0214] Figure 19 illustrates the strain evolution of the 20-MDI-172 intrachain urea PDMS material. During the loading phase, a near-instantaneous strain of approximately 0.5% is observed, typical of an elastic response, followed by a gradual increase to about 1.5% strain (viscoelastic response). During the recovery phase, a near-instantaneous return of strain to a value of approximately 0.9% is noted (again characteristic of the purely elastic response of the material), followed by a gradual return to a value slightly below 0.5% (viscoelastic response). Two Quantitative information from these curves: (i) the maximum deformation, Emax, i.e., the deformation after 250 s, and (ii) the elastic recovery, R e , defined by R e = (ε max - ε r ) / (ε max ), where ε ris the residual strain, i.e., the strain recorded at the end of the test. In the context of the present invention, values ​​of R are targeted e low to ensure that the materials will retain their dimensional stability during use.

[0215] Table 7 presents the values ​​of Emax and R e measured at 20 °C and 40 °C. For the chemically crosslinked reference product (entry 1, Table 7), Emax = 50% and R e = 80%. For intrachain urea PDMS, 20-MDI-172 (entry 2, Table 7), Emax = 1.7% and R e= 79%. Therefore, the recovery of physically crosslinked 20-MDI-172 is equivalent to that of the chemically crosslinked reference product. However, Emax is much lower for 20-MDI-172, indicating that the system deforms much less under stress and is therefore more rigid. While it is difficult to say to what extent this would be a problem if this new material were used in a real-world application, it can be assumed that a higher rate of deformation in response to stress would be desirable, particularly after applying a dressing to a patient.

[0216] [Table 7] Maximum deformation and elastic recovery of polymer blends at 20 and 40 °C

[0217] influence of the mass fraction of PDMS-u-Bz>

[0218] For the MX-Bz series (entries 3 to 5 of Table 7), the increase in the mass fraction of PDMS with hanging ureas, 50-PDMS-u-Bz, results in a progressive increase in Emax Qusqu' to approximately 9% in the case of M- 40-Bz).

[0219] <Influence of the nature of the PDMS-u-YY pendant group>

[0220] For the M-30-YY series (entries 4 and 6 to 9 in Table 7), in all cases, the addition of 50-PDMS-u-YY again results in an increase in Emax and a decrease in R e Among all the systems, M-30-Fmoc stands out with the lowest Emax value in the series and a recovery rate R e greater than 70%, regardless of temperature. This trend suggests that this system is the most cohesive of the series, presumably due to the nn interactions that can develop between the aromatic groups of the MDI units of 20-MDI-172 and the Fmoc functions of 50-PDMS-u-Fmoc.

[0221] Thus, these creep measurements indicate that the developed systems have a higher risk of flow during use. However, some of them (notably M-30-Fmoc) exhibit recovery values ​​very close to the reference system, even at 40°C. It would be necessary to determine whether the maximum strain values, Emax, which are lower than the reference value, are compatible with the application.

[0222] <2.3.3.4 Relaxation Trials>

[0223] All MX-YY samples were studied during a relaxation test consisting of subjecting the sample to a strain s = 1% for 60 seconds and studying the evolution of the relaxation modulus G(t). The experiment was performed at four different temperatures: 20, 40, 60, and 80 °C. Figure 20 shows the time evolution of the normalized relaxation modulus, G(t) / G(0), for sample 20-MDI-172. An exponential decrease in G(t) / G(0) is observed, becoming increasingly rapid as the The temperature increases. This response indicates that the materials effectively relax the stresses associated with imposed deformation. It is typical for a physically cross-linked network whose cross-linking nodes are dynamic. This is indeed the case for urea-urea hydrogen bonds, which can form and break reversibly on short timescales. Although this phenomenon is desirable for restoring the shape of materials at high temperatures, it can pose a problem during use. Here, the materials relax the stresses very rapidly at 40°C. The impact of this phenomenon under conditions simulating the actual use of a dressing should be studied in more detail, particularly by considering the typical deformations to which a dressing may be subjected.

[0224] Conventionally, the relaxation time, T, is considered to be the time for which G(t) / G(0) = 1 / e. Plotting ln(τ) against ln(1 / T) generally yields a linear curve, reflecting behavior that follows an Arrhenius distribution. Using linear regression, the slope provides access to an activation energy, E. a , which reflects the temperature dependence of the relaxation phenomenon. Plus E a The lower the E value, the faster the system relaxes at low temperatures. a The measurements for the different systems are reported in Table 8.

[0225] [Table 8] Activation energy of polymer mixtures 5 M-30-Ad 20 7 M-30-C₁₄ 23 8 M-30-Fmoc 42

[0226] Clearly, the introduction of PDMS-u-YY results in a marked decrease in E acompared to the 20-MDI-172 reference system. Pendant urea PDMS accelerate relaxation phenomena, a trend that is again interpreted as a reduction in the effective physical crosslinking rate of the networks. However, a notable exception is the M-30-Fmoc system, for which E a The concentration does not decrease following the introduction of PDMS with pendant urea. Surprisingly, a slight increase is even observed. Again, this observation suggests that this system is the most cohesive in the series, likely due to the nn interactions of the aromatic rings.

[0227] <2.3.3.5 Tack tests>

[0228] Finally, the adhesion of these systems was studied through preliminary rheometer tests consisting of studying the evolution of the normal force, FN, following a compression of the sample between the two planes of the geometry followed by a controlled speed withdrawal (1 mm / s) of the high head.

[0229] Figure 21 illustrates the evolution of FN for different samples, including the reference system (chemically crosslinked). In this case, a rapid evolution of FN is observed up to a value of approximately -4 N, characteristic of the material's compression phase. Subsequently, the progressive shrinkage of the geometry leads to a gradual increase in FN until reaching an equilibrium value of approximately -0.5 N. This behavior reflects the maintenance of contact between the sample and the upper head of the geometry during the shrinkage phase, thus indicating the sample's adhesion to the geometry. The larger the area between the curve and the x-axis, the stronger the adhesion.

[0230] The curve for sample 20-MDI-172, intrachain urea PDMS, is also available in Figure 21. In this case, a rapid decrease in FN to a value of -8 N is observed during the compression phase, followed by an almost instantaneous return to zero during the shrinkage phase. This behavior is typical of a material that exhibits little or no adhesion. The curves recorded for samples M-20-Bz, M-30-Bz, and M-40-Bz indicate that adhesiveness increases as the mass fraction of pendant urea PDMS, PDMS-u-Bz, increases. These preliminary results confirm what has been observed with this series of samples. They also suggest that these systems remain significantly less adhesive than the reference product (chemically crosslinked).

[0231] The curves for the M-30-YY samples indicate that the nature of the pendant group has relatively little impact on adhesion properties. However, the M-30-Fmoc system again stands out from the rest of the series, exhibiting slightly weaker adhesion. In this case, the greater cohesion of the system due to nn interactions of the aromatic rings could lead to a decrease in the material's adhesiveness.

[0232] Although these 20-MDI-172-based systems do not achieve performance comparable to that of the reference product (chemically crosslinked), they highlight several areas for improving the adhesion of these physically crosslinked systems. Based on this, further optimizations can be considered to try to increase their adhesion.

[0233] Specifically, reducing the flow temperature should decrease the average entanglement of the materials and thus improve adhesion. For example, the 5-MDI-50 and 20-PDMS-u-Bz (60 / 40) mixture has a Tec of 98 °C and a G' (20 °C) of 668 kPa. Comparing the tack of this material to that of the reference product (chemically crosslinked) and the 40-M-Bz system (Figure 22), it can be observed that the tack properties are significantly improved and approach those of the reference product.

[0234] <3. Conclusions>

[0235] Within the scope of the present invention, new physically crosslinked PDMS systems are described, intended to replace chemically crosslinked systems. These new materials must have mechanical and adhesion properties close to those of the chemically crosslinked reference system, with a flow temperature that allows their processing by extrusion, preferably around 100 °C.

[0236] To meet these specifications, a first PDMS system with intrachain ureas was studied. Without limiting ourselves to a single possible interpretation, it is postulated that the intrachain urea-urea hydrogen bonds constitute the nodes of physical crosslinking. Regarding the nature of the diisocyanate linker, this impacts the strength of the hydrogen bonds that form between the chains and therefore the apparent degree of physical crosslinking of the networks. In turn, this impacts the value of the elastic modulus and the flow temperature, Tec. The results obtained indicate that for To achieve flow temperatures >100 °C, it is preferable to work with aromatic diisocyanates that allow for TT-TT interactions, in addition to urea-urea interactions. MDI has emerged as an excellent candidate. Naphthalene diisocyanate or toluene diisocyanate could also be considered.

[0237] The length of the PDMS block is another important parameter. Shorter PDMS blocks lead to harder materials (high elastic modulus), and vice versa. This phenomenon is directly related to the increase in urea density along the chain of the resulting polymer. Within the scope of the present invention, it has been established that PDMS blocks of approximately 20 kg / mol allow the production of materials with elastic moduli on the order of 100 kPa (a value compatible with the specifications). At the same time, the flow temperature of such a system remains high, a phenomenon that appears to be linked to the increased degree of entanglement. Indeed, polymers resulting from the polymerization of high molecular weight prepolymers themselves exhibit a high molecular weight, exceeding the inter-entanglement molecular weight of PDMS (between 15 and 30 kg / mol according to literature references).The entanglements then contribute to the elasticity of the network and its maintenance at high temperature.

[0238] Another important parameter that has been exploited to control the properties of these materials is the degree of ethylation of the urea groups, and / or their substitution with urethane groups. In both cases, this results in weaker physical crosslinking nodes (weaker hydrogen bonds), and therefore materials with lower elastic modulus and flow temperature.

[0239] Although some PDMS with intrachain ureas meet the specifications in terms of mechanical and rheological properties, they are, on the other hand, "non-adhesive" (non-sticky) materials which are not a priori suitable for dressing application.

[0240] This lack of adhesiveness could be partly explained by the very high regularity of the organization of the linear PDMS urea intrachains. Indeed, adhesiveness is generally a characteristic of poorly cross-linked networks, with numerous defects (e.g., dangling chains, branches) that form weak bonds with the surface to which the material adheres. Thus, the high regularity of the PDMS urea intrachain networks provides them with good cohesion but does not offer sufficient macromolecular mobility for good adhesion properties.

[0241] To circumvent this limitation, a new system involving the development of PDMS with pendant ureas has been proposed. This architecture allows for the introduction of branches and pendant chains to achieve a more "disordered" physical crosslinking and thus improved adhesion. At room temperature, PDMS with pendant ureas are highly sticky viscoelastic liquids, confirming that their molecular architecture induces adhesive behavior. However, they cannot be used as is in the intended applications due to their lack of cohesion and therefore dimensional stability.

[0242] To combine cohesion and adhesion, the strategy involved using mixtures of PDMS with intrachain urea and PDMS with pendant urea. This made it possible to obtain materials whose dimensions remain stable at room temperature, with elastic moduli on the order of 100 kPa, flow temperatures above 100 °C, and capable of adhering to various types of surfaces, including skin, metal, Teflon, and glass.

Claims

Demands

1. Composition comprising: (1) a polymer formed by a reaction of a polydimethylsiloxane (PDMS) (la) comprising terminal amine groups -NH2 or -NHR, R being an alkyl group and preferably methyl or ethyl, with a compound (lb) comprising at least two isocyanate groups (-N=C=O), in order to obtain a polymer (1) comprising intrachain urea groups; (2) a polymer formed by a reaction of a polydimethylsiloxane (PDMS) (2a) comprising -NH2 side groups with a compound (2b) comprising a single isocyanate group (-N=C=O), in order to obtain a polymer (2) comprising urea side groups.

2. Composition according to claim 1, wherein the polydimethylsiloxane (PDMS) (la) comprising amine terminal groups has the following molecular formula (A): [Chem. 1] The compound (lb) comprising at least two isocyanate groups is a diisocyanate of formula (B): [Chem. 2] (B), the reaction of polydimethylsiloxane (PDMS) (la) of formula (A) with a diisocyanate (lb) of formula (B), allowing to obtain a polymer (1) including a formula string (C): in which - x represents an integer greater than or equal to 10; - n represents an integer greater than or equal to 1; - Ri represents hydrocarbon groups which can be saturated, linear or branched and which contain between at least 1 and at most 6 carbon atoms, preferably between at least 2 and at most 4 carbon atoms, more preferably 3 carbon atoms; - R2 represents a hydrogen atom or hydrocarbon groups that may be saturated, linear or branched, and that contain between at least 1 and at most 6 carbon atoms, preferably methyl or ethyl; and - Li represents a saturated hydrocarbon group, linear or branched, cyclic or acyclic, or an unsaturated hydrocarbon group, linear or branched, comprising at least one double bond and / or at least one aromatic ring.

3. Composition according to claim 1 or 2, wherein polydimethylsiloxane (PDMS) (la) comprises at least two primary amine terminal groups (-NH2), and preferably comprises terminal groups -(CH2)sNH2 and / or -(CH2)-(CH)CH3-(CH2)NH2, and / or Ri may be selected from the following groups, the symbol * indicating a branch point: (Rl-1) [Chem. (Rl-2) [Chem. 5].

4. Composition according to any one of claims 1 to 3 wherein polydimethylsiloxane (PDMS) (la) comprises at least two secondary amine terminal groups, preferably -NH(ethyl) or -NH(methyl) groups and / or R2 may be selected from the following groups, the symbol * indicating a branch point: (R2-1 [Chem. 6]) * — CH3 (R2-2) [Chem. 7] * — CH2 — CH3 (R2-3) [Chem. 8]

5. Composition according to any one of claims 1 to 4, wherein polydimethylsiloxane (PDMS) (la), comprising at least two amine terminal groups, a starting material in the preparation of polymer (1), has a number molecular weight (Mn) of at least 500 g / mol -1 and at most 150,000 g / mol -1 , preferably of at least 2000 g / mol -1 and at most 30,000 g / mol -1, and / or the number of units x is at least 10 and at most 900.

6. Composition according to any one of claims 1 to 5, wherein the compound (lb) comprising at least two isocyanate groups (-N=C=O) is selected from alkyl diisocyanates, aromatic diisocyanates and / or alicyclic diisocyanates.

7. A composition according to any one of claims 2 to 6, wherein L1 is a hydrocarbon structure such that at least 4 and at most 12 carbon atoms separate the two branch points by the shortest path, and preferably L1 is chosen among the following groups, the symbol * indicates a carbon atom that is part of the L1 structure and is also a branch point: (Ll-1) [Chem. 9] (Ll-2) [Chem. 10] (Ll-3) [Chem. 11] (Ll-4) [Chem. 12] (Ll-5) [Chem. among which, for the (Ll-4) structure, the two isocyanate groups can be present on any of the carbon atoms in ortho, meta, or para positions relative to the CH2 group located between the two aryl groups, and preferably the two isocyanate groups are in positions 4,4' or 2,4' or 2,2, and among which, for the (Ll-5) structure, the two isocyanate groups can be present on any of the carbon atoms in ortho, meta or para positions relative to the CH3 group, and preferably the two isocyanate groups are in positions 2,4 or 2,6.

8. Composition according to claim 7, wherein the molecule comprising at least two isocyanate groups (-N=C=O) is an aromatic diisocyanate, and preferably L1 is a hydrocarbon structure corresponding to (L1-4), more preferably wherein the two isocyanate groups are in positions 4,4'.

9. Composition according to claim 1, wherein polydimethylsiloxane (PDMS) (2a) having amine side groups has the following molecular formula (D): [Chem. 14] Compound (2b) comprising at most one isocyanate group is a monoisocyanate of formula (E): [Chem. 15] (E), the reaction of polydimethylsiloxane (PDMS) (2a) of formula (D) with y3 molar equivalent(s) of monoisocyanate of formula (E), allowing to obtain a polymer (2) of formula (F): [Chem. 16] - yl and y2 represent integers greater than or equal to 1; - y3 represents an integer between at least 0, preferably at least 1, and at most y2; - R3 represents a hydrocarbon group that can be saturated, linear or branched, and that contains between 1 and 6 carbon atoms, preferably between 2 and 4 carbon atoms, more preferably 3 carbon atoms, or R3 can be -(CH2)3-NH-(CH2)2-; and - L2 represents a saturated hydrocarbon group, linear or branched, cyclic or acyclic, or an unsaturated hydrocarbon group, linear or branched, comprising at least one double bond and / or at least one aromatic ring; L2 represents a saturated hydrocarbon group, linear or branched, cyclic or acyclic, in which one or more CH2s have been replaced by O or C=O; or an unsaturated hydrocarbon group, linear or branched, comprising at least one double bond and / or at least one aromatic ring and in which one or more CH2s have possibly been replaced by O or C=O.

10. Composition according to claim 1 or 9, wherein polydimethylsiloxane (PDMS) (2a) comprises as -NH2 side groups at least primary amine pendant groups (-NH2), and preferably comprises -(CH2)3NH2 pendant groups and / or - (CH2)S-(NH)-(CH2)2-NH2, and / or R3 can be chosen from the following groups, the symbol * indicating a branch point: (Rl-1) [Chem. (Rl-2) [Chem. 18] *-CH2CH2-CH2-NH-CH2-CH2-*

11. Composition according to claim 9 or 10, wherein the number-average molecular weight Mn of polydimethylsiloxane (PDMS) (2a) comprising -NH2 side groups is at least 10 kg / mol and at most 80 kg / mol, preferably at least 20 kg / mol and at most 70 kg / mol, and more preferably at least 40 kg / mol and at most 60 kg / mol.

12. Composition according to any one of claims 9 to 11, wherein the groups -(Si(Me)2-O)- and -(Si(Me)(-(CH2)q-NH2)- O)-, q being an integer of at least 1 and at most 6, constitute (100-z)% and z% respectively, expressed in mol%, of the polymer chain (2a) excluding the terminal -SiMes groups, z is at least 2 mol% and at most 40 mol%, preferably at least 4 mol% and at most 30 mol%, more preferably at least 5 mol% and at most 10 mol%, z being defined by the following equation: [Math. 1]

13. Composition according to any one of claims 9 to 12, wherein the polymer (2a) comprises between 10 and 80 amine groups (-NH2) per chain, preferably between 20 and 60 amine groups (-NH2) per chain.

14. A composition according to any one of claims 9 to 13, wherein the compound (E) comprising a single isocyanate group (-N=C=O) is selected from alkyl monoisocyanates, aromatic monoisocyanates, alicyclic monoisocyanates, or alkyl carbonyl monoisocyanates, or phenyl carbonyl monoisocyanates, or alkoxy carbonyl monoisocyanates, or phenoxy carbonyl monoisocyanates, or fluorenylmethoxy carbonyl monoisocyanates.

15. Composition according to any one of claims 9 to 14, wherein L2 is selected from the following groups, the symbol * indicating a carbon atom forming part of the L2 structure and also being a branch point: .

16. Composition according to any one of claims 1 to 15, wherein the sum of the masses of polymers (1) and (2) being of 100% by weight, the quantity of polymer (2) is at least 30% by weight and at most 50% by weight, preferably at least 35% by weight and at most 45% by weight.

17. Use of a composition according to any one of claims 1 to 16, in adhesive products intended to be applied to skin, wounds, hair and / or mucous membranes.

18. Dressing comprising an elastomeric matrix obtained from the composition according to any one of claims 1 to 16.

19. Dressing according to claim 18, wherein the elastomeric matrix has through holes.

20. Dressing according to claim 18 or 19, wherein the elastomeric matrix further contains one or more active ingredients for the treatment of a wound, the active ingredients being selected from the group consisting of: antibacterials, antiseptics, pain relievers, anti-inflammatories, healing promoters, and anesthetics.

21. Dressing according to any one of claims 18 to 20, wherein the elastomeric matrix is ​​present in the form of an adhesive border enabling the dressing to be fixed to the skin surrounding a wound to be treated.

22. Dressing according to any one of claims 18 to 21, wherein the elastomeric matrix is ​​present in the form of a film having a thickness of at least 20 pm and at most 50 pm.

23. Polymer of formula (F): [Chem. 26] - y1 and y2 represent integers greater than or equal to 1; - y3 represents an integer between 1 and y2; - R3 represents a hydrocarbon group that can be saturated, linear or branched, and that contains between at least 1 and at most 6 carbon atoms, preferably between at least 2 and at most 4 carbon atoms, more preferably 3 carbon atoms, or R3 can be R3 can be - (CH2)3-NH-(CH2)2-; and - L2 represents a saturated hydrocarbon group, linear or branched, cyclic or acyclic, or an unsaturated hydrocarbon group, linear or branched, comprising at least one double bond and / or at least one aromatic ring; a saturated hydrocarbon group, linear or branched, cyclic or acyclic, in which one or more CH2s have been replaced by O or C=O; or an unsaturated hydrocarbon group, linear or branched, comprising at least one double bond and / or at least one aromatic ring and in which one or more CH2s may have been replaced by O or C=O.

24. Polymer according to claim 23, wherein R3 can be selected from the following groups, the symbol * indicating a branch point: (Rl-1) [Chem. (Rl-2) [Chem. 28] *-CH2-CH2-CH2-NH-CH2-CH2-*

25. Polymer according to claim 23 or 24, having a number average molecular weight Mn of at least 10 kg / mol and at most 80 kg / mol, preferably of at least 20 kg / mol and at most 70 kg / mol, and more preferably of at least 40 kg / mol and at most 60 kg / mol.

26. Polymer according to any one of claims 23 to 25, wherein the groups -(Si(Me)2-O)- and -(Si(Me)(-(CH2)q-NH2)-O)-, q being an integer of at least 1 and at most 6, constitute (100-z)% and z% respectively, expressed in mol%, of the polymer chain excluding the terminal -SiMes groups, z is at least 2 mol% and at most 40 mol%, preferably at least 4 mol% and at most 30 mol%, more preferably at least 5 mol% and at most 10 mol%, z being defined by the following equation: [Math. 2]

27. ​​Polymer according to any one of claims 23 to 26, comprising between 10 and 80 groups of -R3-NH- lateral branches per chain, preferably between 20 and 60 groups per chain.

28. Polymer according to any one of claims 23 to 27, wherein L2 is selected from the following groups, the symbol * indicating a carbon atom forming part of the L2 structure and also being a branch point: (L2-1) [Chem. (L2-2) [Chem. (L2-3) [Chem. .

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